1. Field of the Invention
The present invention relates to a technique of laying a thin and band-shaped tape, and particularly to a technique of laying a copper foil and an insulation tape for use in a thin film-type photovoltaic devices.
2. Background Art
There is well known a photovoltaic devices which converts solar energy into electric energy. A crystalline photovoltaic devices is a configuration in which a single-crystalline or poly-crystalline silicon substrate is used. The crystalline photovoltaic cell is a currently dominant but is expensive. On the other hand, a thin film-type photovoltaic devices is formed by depositing thin film-type amorphous silicon on, for example, a glass substrate or the like. There is also a non-silicon thin film-type photovoltaic devices such as CIS. These are all photovoltaic devices.
Usually a thin film-type photovoltaic devices panel is configured with a structure that plural photovoltaic cells are electrically series-connected in one transparent electrode substrate.
FIG. 7 shows a structure of the thin film-type photovoltaic devices panel. A thin film-type photovoltaic devices panel 1 includes plural photovoltaic cells 2 and a peripheral area 3 surrounding the plural photovoltaic cells 2. The plural photovoltaic cells 2 and the peripheral area 3 are insulated each other. Each photovoltaic cell 2 is formed into an elongated rectangular shape along a long side of the photovoltaic devices panel 1, and one of the long sides is an anode and the other is a cathode. Accordingly, the photovoltaic devices panel 1 is configured with the structure that the plural photovoltaic cells 2 are series-connected.
A copper-foil electrode 5 having substantially the same length as the photovoltaic cell 2 is attached to the photovoltaic cell 2 located at the left end of the photovoltaic devices panel 1. A copper-foil electrode 6 having substantially the same length as the photovoltaic cell 2 is attached to the photovoltaic cell 2 located at the right end of the photovoltaic devices panel 1. The plural series-connected photovoltaic cells 2 becomes a direct-current power supply when the electrodes 5 and 6 are connected to a load. In the usage of photovoltaic devices panel 1, the electrodes 5 and 6 are connected to a central junction box 11 via conductors 7 and 8, and the junction box 11 is connected to a connector of load (not shown) to use an electric power generated from the photovoltaic devices panel 1.
The copper-foil conductor 7 extends from the electrode 5 toward the junction box 11, and the conductor 8 extends from the electrode 6 toward the junction box 11. Because the conductors 7 and 8 are conductive materials, a short circuit occurs when the conductors 7 and 8 directly contact the photovoltaic cells 2 located between the electrode 5 and electrode 6. Therefore, insulation tapes 9 and 10 are laid between the conductor 7 and the photovoltaic cells 2 and between the conductor 8 and the photovoltaic cells 2, respectively.
FIG. 8 is an enlarged view of a part of FIG. 7 and shows the relationship A between the electrode 5, the conductor 7, and the insulation tape 9. The relationship A holds true for the relationship B between the electrode 6, the conductor 8, and the insulation tape 10. The relationship B is described by that the electrode 5 can be replaced for the electrode 6, the conductor 7 can be replaced for the conductor 8, and the insulation tape 9 can be replaced for the insulation tape 10 in the description of the relationship A. Therefore the description thereof is omitted in the following description.
When the electrode 5 is placed on the photovoltaic cell 2 located at the left end, the part having a width W of photovoltaic cell 2 at the left end is exposed on one side. The conductor 7 must be connected to the electrode 5, but needs to be electrically insulated from the adjacent photovoltaic cell 2. Therefore, it is necessary that an end 9a of the insulation tape 9 intrude into the part having a width W of photovoltaic cell 2 at the left end, and it is necessary that the relationship of d<W hold, where d is a gap between the end 9a and the electrode 5.
The photovoltaic cell 2 has a width of about 5 to 6 mm. On the other hand, in order to reduce resistances of the electrode 5 and the conductor 7, there is a demand to widen the width of the copper foil used in the electrode 5 and the conductor 7 as much as possible. Frequently, performance of a photovoltaic module is evaluated by its power generation efficiency. The power generation efficiency is efficiency per area, and there is also a demand to reduce a width of an electrode cell that is not used for the power generation. The photovoltaic devices panel 1 has a width of about 1000 mm, and the conductor 7 or the insulation tape 9 has a length of about 400 mm. The accuracy of cutting the conductor 7 or the insulation tape 9 is important to above demands, while only the width W is very narrow, ranging from about 1 to 2 mm. Therefore, the relationship of d<W cannot be secured unless a position at which the conductor 7 or the insulation tape 9 is laid is accurately determined, and the problem above can hardly be solved.